From 08143359141000fcf730ebffb58f4ba46b35e9c1 Mon Sep 17 00:00:00 2001
From: Serhiy Storchaka <storchaka@gmail.com>
Date: Thu, 16 Jun 2022 11:16:57 +0300
Subject: [PATCH 1/2] gh-93820: Pickle enum.Flag by name

---
 Lib/enum.py                                   | 11 ++++-
 Lib/test/test_enum.py                         | 44 ++++++++++++++++++-
 ...2-06-16-11-16-53.gh-issue-93820.00X0Y5.rst |  1 +
 3 files changed, 53 insertions(+), 3 deletions(-)
 create mode 100644 Misc/NEWS.d/next/Library/2022-06-16-11-16-53.gh-issue-93820.00X0Y5.rst

diff --git a/Lib/enum.py b/Lib/enum.py
index ee32d5d4e058bc..e68f741933675b 100644
--- a/Lib/enum.py
+++ b/Lib/enum.py
@@ -1370,7 +1370,16 @@ class Flag(Enum, boundary=STRICT):
     """
 
     def __reduce_ex__(self, proto):
-        return self.__class__, (self._value_, )
+        for m in self:
+            rest = self._value_ & ~m._value_
+            if rest:
+                return _or_, (m, self.__class__(rest))
+            else:
+                break
+        if self._name_ is None:
+            return self.__class__, (self._value_,)
+        else:
+            return getattr, (self.__class__, self._name_)
 
     _numeric_repr_ = repr
 
diff --git a/Lib/test/test_enum.py b/Lib/test/test_enum.py
index 28594b010d80d3..33b3f9dae74a42 100644
--- a/Lib/test/test_enum.py
+++ b/Lib/test/test_enum.py
@@ -65,10 +65,27 @@ class FloatStooges(float, Enum):
     class FlagStooges(Flag):
         LARRY = 1
         CURLY = 2
-        MOE = 3
+        MOE = 4
 except Exception as exc:
     FlagStooges = exc
 
+class FlagStoogesWithZero(Flag):
+    NOFLAG = 0
+    LARRY = 1
+    CURLY = 2
+    MOE = 4
+
+class IntFlagStooges(IntFlag):
+    LARRY = 1
+    CURLY = 2
+    MOE = 4
+
+class IntFlagStoogesWithZero(IntFlag):
+    NOFLAG = 0
+    LARRY = 1
+    CURLY = 2
+    MOE = 4
+
 # for pickle test and subclass tests
 class Name(StrEnum):
     BDFL = 'Guido van Rossum'
@@ -2956,9 +2973,32 @@ def test_programatic_function_from_dict(self):
     def test_pickle(self):
         if isinstance(FlagStooges, Exception):
             raise FlagStooges
-        test_pickle_dump_load(self.assertIs, FlagStooges.CURLY|FlagStooges.MOE)
+        test_pickle_dump_load(self.assertIs, FlagStooges.CURLY)
+        test_pickle_dump_load(self.assertEqual,
+                        FlagStooges.CURLY|FlagStooges.MOE)
+        test_pickle_dump_load(self.assertEqual,
+                        FlagStooges.CURLY&~FlagStooges.CURLY)
         test_pickle_dump_load(self.assertIs, FlagStooges)
 
+        test_pickle_dump_load(self.assertIs, FlagStoogesWithZero.CURLY)
+        test_pickle_dump_load(self.assertEqual,
+                        FlagStoogesWithZero.CURLY|FlagStoogesWithZero.MOE)
+        test_pickle_dump_load(self.assertIs, FlagStoogesWithZero.NOFLAG)
+
+        test_pickle_dump_load(self.assertIs, IntFlagStooges.CURLY)
+        test_pickle_dump_load(self.assertEqual,
+                        IntFlagStooges.CURLY|IntFlagStooges.MOE)
+        test_pickle_dump_load(self.assertEqual,
+                        IntFlagStooges.CURLY|IntFlagStooges.MOE|0x30)
+        test_pickle_dump_load(self.assertEqual, IntFlagStooges(0))
+        test_pickle_dump_load(self.assertEqual, IntFlagStooges(0x30))
+        test_pickle_dump_load(self.assertIs, IntFlagStooges)
+
+        test_pickle_dump_load(self.assertIs, IntFlagStoogesWithZero.CURLY)
+        test_pickle_dump_load(self.assertEqual,
+                        IntFlagStoogesWithZero.CURLY|IntFlagStoogesWithZero.MOE)
+        test_pickle_dump_load(self.assertIs, IntFlagStoogesWithZero.NOFLAG)
+
     @unittest.skipIf(
             python_version >= (3, 12),
             '__contains__ now returns True/False for all inputs',
diff --git a/Misc/NEWS.d/next/Library/2022-06-16-11-16-53.gh-issue-93820.00X0Y5.rst b/Misc/NEWS.d/next/Library/2022-06-16-11-16-53.gh-issue-93820.00X0Y5.rst
new file mode 100644
index 00000000000000..70bb1e6c0cd764
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2022-06-16-11-16-53.gh-issue-93820.00X0Y5.rst
@@ -0,0 +1 @@
+Pickle :class:`enum.Flag` by name.

From 79f7f7e9a25cbe55904a373b4f00f2fd0ac16ee6 Mon Sep 17 00:00:00 2001
From: Serhiy Storchaka <storchaka@gmail.com>
Date: Thu, 16 Jun 2022 16:10:01 +0300
Subject: [PATCH 2/2] Optimize.

---
 Lib/enum.py | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/Lib/enum.py b/Lib/enum.py
index e68f741933675b..71f0abfe847db5 100644
--- a/Lib/enum.py
+++ b/Lib/enum.py
@@ -1370,16 +1370,21 @@ class Flag(Enum, boundary=STRICT):
     """
 
     def __reduce_ex__(self, proto):
-        for m in self:
-            rest = self._value_ & ~m._value_
+        cls = self.__class__
+        unknown = self._value_ & ~cls._flag_mask_
+        member_value = self._value_ & cls._flag_mask_
+        if unknown and member_value:
+            return _or_, (cls(member_value), unknown)
+        for val in _iter_bits_lsb(member_value):
+            rest = member_value & ~val
             if rest:
-                return _or_, (m, self.__class__(rest))
+                return _or_, (cls(rest), cls._value2member_map_.get(val))
             else:
                 break
         if self._name_ is None:
-            return self.__class__, (self._value_,)
+            return cls, (self._value_,)
         else:
-            return getattr, (self.__class__, self._name_)
+            return getattr, (cls, self._name_)
 
     _numeric_repr_ = repr